Galvanometer.



No. 706,982. Patented Aug. l2, I902.

C. L. B. E. MENGES.

GALVANOMETER.

(Application filed Dec. 28 1897.)

(No Model.)

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UNITED STATES PATENT OFFICE.

CHARLES LUDlVIG RUDOLPH ERNEST MENGES, OF THE HAGUE, NETHER- LANDS.

GALVANOMETER.

SPECIFICATION forming part of Letters Patent No. 706,982, dated August 12, 1902. Application filed December 23 1897. Serial No, 663,249. (No model.)

To wilwlwm it may concern:

Be it known that I, CHARLES LUDWIG RU- DOLPH ERNEST MENGES, electrician, asubject of the Queen of the Netherlands, residing at 82 to 84cl3alistraat,The Hague, in the Kingdom of the Netherlands, have invented certain new and useful Improvements in or Relating to Galvanometers, (for which I have obtained patents in Great Britain, No. 1,265, dated January 18, 1895; in France, No. 24:8,956, dated July 17, 1895; in Belgium, No. 116,592, dated July 18, 1895, and in Germany, No. 83,180, dated January 5, 1895,) of which the following is a specification, reference being I 5 had to the accompanying drawings.

My invention relates to self-controllable electromagnetic galvanometers-that is to say, to galvanometers that do not require any separate'instrument for controlling them-- and especially to galvanometers intended to be used as volt meters or ammeters.

According to my invention agalvanometer is provided wherein the magnetic field is controlled by means of the attraction of one part 25 of the magnetic circuit upon another part in combination with suitable means for varying themagnetic flux. If the magnetic field in such a construction changes, then with the aid of the said controlling apparatus the field can be readjusted to its original strength, so that the deflections of an indicating-pointer produced by given electric currents will be the same as when the apparatus was originally graduated.

3 5 My invention may be applied to various systems of electromagnetic galvanometers and can be performed chiefly in the three following methods: first, a method in which the controlling apparatus itself acts also as a 40 current-meter; secondly, a method in which the controlling apparatus conducts the magnetic flux directly to the movable part of the current-meter, and, thirdly, one in which the controlling apparatus forms aseparate part of 5 the magnetic circuit between the magnet and the current meter proper. These three methods are illustrated by the accompanying drawings, in which- I Figure 1 is a front elevation, and Fig. 2 is a plan, of an improved form of galvanometer embodying my invention, the fixed 1nagnet and soft-iron fkeeper being removed. Figs. 3 and 4: are front elevations of galvanometers, illustrating the application of my invention to existing types of galvanometers. 5 5

Like letters denote corresponding parts throughout the drawings.

Referring now to Fig. l, which shows an improved form of galvanometer or current-meter illustrating, by way of example, my first method of controllingsuch instruments-viz.,

a method in which the controlling apparatus itself acts also as a current-meter--N' m S is a magnet to which are attached pole-pieces Between the said pole-pieces is a movable device consisting of magnetizalole pole projections 01 n 72 and s 8, carried by the upper and lower ends, respectively, of a rod or spindleA, of non-magnetic material. The device at A s is pivoted at its lower end in a cylindrical recess 8* in the polepiece S and at its upper end, which is conical, in a conical recess N* in the pole-piece N. The bearings N? and S in the pole-pieces are so arranged that the device n A s has a small 75 amount of play in an axial direction. 0n

account of the conical shape of the upper part of the device a A s the magnet exerts an upward attraction thereon, and if such attraction is greater than the weight of the said device the latter will be lifted against the conical recess N. The device A .9 may be moved up and down when desired by a suitable hand contrivance comprising a rod B, adapted to move in a guide-block 0, secured to the pole-piece S and carrying at its upper end a spring-finger D, adapted to engage at its two extreme positions with the upper and lower faces of an annular groove A, formed by two collars on the rod A. A 0 spiral spring E, which surrounds the rod B between the fingerD and the block C,. serves to keep the said finger D normally out of contact with and midway between the two faces of the groove A, and thus the rotary move- 5 ment of the device at A sis not impeded. A knob or button B is provided on the rod B, preferably outside the case E of the instrument, by means of which an axial movement may be imparted to the movable device 02 A s when desired. The lower part of the pole projection :a n n is of a semicircular or halfring shape, as shown in Fig. 2, and is arranged to move in a wire coil or Solenoid G. TlllS coil is not shown in Fig. 1, but the dotted arrow indicates the direction in which the current should pass around the curved part of the pole projection n. A spiral spring H, surrounding the spindle Aand connected thereto at one end and bearing against a fixed a abutment-finger H at the other end, furnishes 1o a force which tends to counteract the turning action of the solenoid G on the lower semicircular part of the pole projection n n n. The resulting deflection due to the turning of the device 71, A s by the action of the solenoid G may be indicated by means of a fixed pointer (not shown) in connection with a movable cylindrical scale I, which latter is carried by an arm A attached to the rod or spindle A.

J is a soft-iron armature or keeper movable in guides by means of a screw K, whereby its poles can be caused to approach or to recede from the fixed pole-pieces N" S. The said armature acts as a magnetic shunt to the magnetic lines. Now disregarding that part of the magnetic flux of the magnetN m S which is lost by leakage all of the magnetic lines that do not pass through the keeper J pass through the fixed pole-pieces N S and the movable pole projections n n n and s s.

By'shifting the position of the keeper J we 'may obtain just sufficient flux through the movable device 72 A s to furnish an upward magnetic attraction equal to the weight ,of

. the device n A s, and thus maintain the said.

device floating in the field. The equilibrium, however, is unstable. Therefore if the device it A s be moved by the finger D on the rod 13 up or down in it's bearings it will when it passes a certain intermedi- 40 ateposition jump over tothe other extreme position, showing thereby that there is exact equilibrium in thatintermediate position. If

the instrument be now calibrated with respect to the deflections produced by various strengths of current,the instrument will again indicate correctly if, after some alterations in the magnetic field, the magnetic state of the movable device n A sis restored to its original value by suitably shifting the keeper or armature J. The magn-etic'leakage cannot have a detrimental eflect, since it depends on the shape or configuration of the parts, which remains practically the same, and on the magnetic state, which when-altered isagain restored to the originalstate'in the main parts of the instrument by shifting thekeeper J. Some variable magnetic leakage may occur between the poles of the keeper and the fixed pole-pieces N S; butthese points ofleakage are so far away from the movable device as to have no detrimental efas a Deprez or Ayrton and Perry. an1meterv in which the current-meter proper consists of a movable needle 41 s, placed between coils opposite end is capable of being lifted by the I attraction of the adjacent part S of the polepiece and is provided with an' adjustable counterpoise-weight O. A suitable arrangement may be employed for moving the controlling-piece S up and down to control the attraction of the magnet,'as'hereinbefore ex plained, similar to that described with reference to Fig. 1. The two pins P Pin this case serve as projections for the spring-finger to engage with. The necessary changes in the magnetic flux are obtained by varying the distance between the adjustable magnet N m S and the fixed portions of the pole-pieces N and S by means of the adjusting-screw K. By shifting the counterpoise O and by a corresponding alteration of the magnetic flux by means of thescrew K,- so as to maintain the piece S floating in the field, a predetermined deflection of the needle may be obtained for a given strength of current. y

In the instrument shown in Fig. 4, illustrates my third method, the magnetic lines from the magnet N m S pass through the divided pole projections S S to a polepiece S and thence to the pole-piece N by way of the cylindrical core Q, which is fixed midway between the faces of't'ne pole-pieces N and S Around the core Q a wire coil G is adapted to swing, as in the well-known dArsonval galvanometer. The part S is adapted to slide within the pole-piece S so as to be easily movable in a vertical direction. counterpoise weight 0 acts against the attraction of the pole S on the movable part S The movement of the part S is effected by means of the spring-finger D, operated by the handle B. The required changes in the magnetic flux are obtained by causinga softiron armature or keeperJ to approach or recede from the pole-pieces N S. The movement of the movable pole-piece S 'may be in which dicated on an enlarged scale by means of a ously be applied to various other forms of instrument.

I may also apply the constant magnetic field obtained in the manner liereinbefore described for calibrating or checking the constants of ballistic galvanometers. For instance, an apparatus may be used the main features of which are similar to that described with reference to Fig. 4. If the terminals of being cylindrical and surrounded by the other pole-piece. In that case I use a cylindrical coil, which I let drop through the field, as in Hibberts instrument.

In all the forms of apparatus I have described by way of example I have utilized gravity as the controlling force; butI may obviousl y also employ a spring for this purpose. I sometimes prefer to use electromagnets instead of the permanent magnets hereinbefore described.

What I claim isi 1. The combination of a magnet, a movable electrically-acting device situated in the mag I netic flux produced by said magnet, means for measuring the said magnetic flux, and means for varying the said magnetic flux and adjusting it to the required magnitude as indicated by the said measuring means, substantially as described.

2. The combination of a magnet, a movable electrically-actin g device in the field produced by said magnet, a magnetic circuit including an adjustable part and a movable part, and means for adjusting and measuring the magnetic attraction acting on said movable part so as to adjust the magnetic flux to the required magnitude as shown by'the said means for measuring the magnetic attraction, substantially as described.

3. The combination of a magnet, a movable electrically-actin g device arranged in the field of said magnet, a magnet-circuit provided with a movable part, means for measuring the magnetic attraction on that movable part, and means for varying the magnetic flux so that the magnetic attraction balances the effect of the counteracting force on the said movable part of the magnetic "circuit, substantially as described. I i

4. The combination ofa magnet, a magnetic circuit provided with a movable part and an adjustable part, means for varying the relative position of the said adjustable part in order to adjust the magnetic flux so as to produce a definite attraction on the movable part of the magnetic circuit, and means for measuring said attraction, substantially as described.

5. The combination of a magnet, a magnetic circuit provided with a movable part, an adjustable magnet-shunt to the magnetic circuit, means for adjusting said shunt relatively to said magnetic circuit in order to adj net the main magnetic flux so as to produce a definite attraction on the said movable part of the magnetic circuit, and means for measurin g said attraction,substantially as described.

6. In a galvanometer, the combination of a magnet, an armature adjustable toward and from said magnet, pole-pieces projecting toward each other, a deflectable device arranged vertically between said pole-pieces,and means for raisin g said device toward the upper polepiece to the position where the-magnetic attraction counteracts the force of gravity, substantially as described.

7. In a deflectable device fora galvanometer, the combination of a vertical rod or spin-. dle of non-magnetic material, a magnetic piece orpole extending from the top of said rod in an inclined direction and terminating in a curved piece, a stationary segmental coil or solenoid acting on said curved piece; and

a second magnetic piece or pole extending upward from the lower end of the aforesaid rod, and terminating opposite the end. of the curved portion of thefirst pole-piece, substantially as described.

8. In a galvanometer, the combination of a magnet, pole-pieces having recesses to receive the extremities of a deflectable device, a magnet-piece on said device forming an extension of the upper pole-piece and terminat- I ing in a curved portion, asegmental solenoid acting on said curved portion and a second magnetic piece forming an extension of the lower pole-piece, substantially as described. In testimony whereof I have hereunto set my hand this 6th day of December, 1897.

CHARLES LUDWIG RUDOLPH ERNEST MENGES. 

